Scroll type fluid displacement apparatus incudes a pair of scrolls with end plates and involute spiral wraps having flank surfaces and axial tips. The flanks of the wrap on one scroll contact the flanks of the wrap on the other scroll and the axial tips carry seals which contact the end plate of the adjacent scroll to form sealed fluid pockets. Orbital movement of the pair of scrolls relative to each other will move the sealed pockets toward the center of the scrolls to compress or pump fluid.
Sealing between the axial tips of the wraps and the end plates is required to obtain high efficiency in scroll type fluid displacement machines. Axial tip sealing is complicated by axial expansion of the wraps due to temperature changes. When the scrolls are used in compressors, the temperature at the center of the scrolls is higher than the temperature at the outer edge of the scrolls. These temperature variations result in uneven axial expansion of the scroll wraps. The axial tip seals have to accommodate the uneven expansion of scroll wraps. Pumps and fluid expanders may also be subjected to uneven expansion of scroll wraps due to temperature changes in fluids during expansion or pumping.
Seals for the axial tips of scrolls are commonly die cut from flat sheets of seal material. This cutting procedure results in the loss of a substantial portion of the seal material as scrap. The scrap material is expensive due to high cost components used to make the seal material. There are also disposal costs associated with the scrap seal material.
Involute spiral seals are inserted in axial tip seal grooves by hand. The delicate spiral seals have to be inserted manually. Assembly machines could damage the delicate seal material.
A continuous strip of tip seal material can be formed into an involute spiral and cut to length. Seals formed by such a procedure are delicate. They can easily loose the involute shape and may even revert to a coil similar to their previous rolled shape.